The present invention relates to a type of heat exchanger known as a recuperator. Recuperators are used in conjunction with various power generating devices to increase the operating efficiency of the system. In general, a recuperator pre-heats air prior to combustion within a gas turbine engine, (for example) in heat exchange relationship with the hot exhaust gases. The present invention is more specifically directed to an annular recuperator for use with a gas turbine engine.
Recuperators are specifically designed and required to operate in extreme environments. The hot pass side of the recuperator is subjected to pressurized combustion exhaust gases and temperatures in excess of 1000.degree. F. Meanwhile, the cold pass side of the recuperator receives ambient or precompressed ambient air at temperatures which may be below 0.degree. F. The potentially destructive combination of high pressure differentials, high thermal differentials, and corrosive combustion products is amplified by thermal cycling and startup/shutdown cycles. Thus, the recuperator must be extremely rugged, while being flexible to accommodate thermal growth and cycling.
A number of the problems associated with the design and construction of industrial flat-plate type recuperators are addressed within U.S. Pat. Nos.: 4,246,959; 4,263,964; 4,291,752; 4,291,754; 4,299,868; 4,331,352; 4,377,02; 4,458,866; and 4,511,106 all of which are ourrently assigned to the assignee of the present invention.
While a properly designed recuperator increases the efficiency of the power generating system, there are disadvantages associated with their use. Notably, the recuperator back pressurizes the power plant, decreasing its efficiency. Also, recuperators add substantial weight and size, and they are potentially subject to failure, causing downtime for the power generating system. For mobile applications, such as within ships and land vehicles, the added weight and size considerations become extremely important, and may determine whether the added efficiency of the system is justified.